Answers to the even-numbered assigned problems in Chapts 9--11
The following is a list of the answers to the even-numbered assigned problems.
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Chapter 9
9-12
a) -0.506 rad/s2
b) 16.1 s
9-26
a) atan = 0.180 m/s2, arad = 0, a = 0.180 m/s2
b) atan = 0.180 m/s2, arad = 0.377 m/s2, a = 0.418 m/s2
c) atan = 0.180 m/s2, arad = 0.754 m/s2, a = 0.775 m/s2
9-42 18.0 kg
9-46
a) 29.3 m/s
b) 1.93 × 103 J
9-64
a) H = 3/5 H0
b) There is less potential energy at the second height H than at the first height H0 because some of the initial potential energy has been converted into rotational kinetic energy.
9-70
a) 36.6 m; 28.0 m/s
b) The total mechanical energy of the ball is the same, but the rotation rate of the ball is less at the top of the hill than it was initially. While it moves through the air, the rotation rate of the ball stays the same, so it is less when it returns to the ground than when it started to roll up the hill.
Chapter 10
10-2 28.0 N m, clockwise
10-28
a) 25.8 kg m/s2
b) 4.78 rad/s
c) Ki = 38.7 J; Kf = 61.7 J; the kinetic energy increases because of the positive work done by the woman as she pulls the weights in.
10-34 1.38 rad/s
10-40
b) 1000 N
c) 1.20 m from the end where the 400.0 N force is applied.
10-44
a) 3.41 × 103 N
b) Fh = 3410 N, Fv = 7600 N
10-64
a) 1.19 × 105 N
b) 1.27 × 105 N, directed at 20.7 ° above the horizontal
c) 0.839 rad/s2
10-76
b) 1.32 × 104 N
c) 1.80 × 104 N
10-82 0.675 s
Chapter 11
11-26
a) 0.40 mm
b) 2.0 ms
c) 500 Hz
d) 3140 ras/s
11-28
a) 1.20 m/s
b) 1.11 m/s
c) 36 m/s2
d) +13.5 m/s2
e) 0.360 J
11-58 K = 3/4 E, U = 1/4 E